Communication system networks are known to comprise a plurality of communication systems and a central controller. Each of the communication systems comprises a plurality of communication units, a limited number of communication resources that are transceived via a limited number of repeaters, and a communication resource allocator that allocates the communication resources among the plurality of communication units. The communication units, which may be mobile radios, portable radios, and/or portable radio/telephones, are typically arranged in to communication groups and are generally located throughout the communication system network. Of the communication resources, which may be TDM slot locations, frequency carriers, pair of frequency carriers, or any other RF transmission means, one is selected to function as a control channel. The control channel transceives operational information between the communication units and the central controller via the communication resource allocators.
As is known, a communication unit may establish a communication with other communication units within the communication system network by transmitting an inbound signalling word (ISW) to the central controller via the communication resource allocator of the communication system that the communication unit is located in. Upon receiving the request, the central controller processes it and, if the request is valid, the central controller allocates a communication resource in each of the communication systems that have a communication unit of the targeted talk group in it. The communication systems, which may also be communication sites, are coupled to and controlled by the central controller. If a communication system, or site, loses contact with the central controller, the communication system, or site, operates as an independent communication system but only for communication units that are located within its coverage area.
As is also known, under certain circumstances, communication groups that normally do not communicate with each other may be combined into one group to more efficiently respond to a particular situation. For example, when an emergency condition arises, an operator of a operator station, or console, may elect to combine separate communication groups into one to respond to the emergency condition. Thus, the operator of the console may combine the communication groups of the police department, fire department and state patrol into one communication group to respond to the emergency. When the operator of the console selects to combine groups, commonly known as regrouping, the consoles transmits the request to the central controller. Upon receiving the request, the central controller processes it by regrouping the selected groups in to a super group and allocating a communication resource in each of the communication systems, or sites, to the regrouped communication group whether or not a communication unit of the super group is located within that communication system. This unfortunately wastes communication resources.
In addition, some communication system networks, in each communication system, allocate a communication resource for each communication group of the super group and combine the signalling at the central controller such that, to the communication units, it appears they are all talking on one resource. This becomes very inefficient when a communication system, or site, does not have communication units of all communication groups of the super group located in it. Therefore, a need exists for a method that will allow the central controller to allocate only one communication resource in each communication system that has a communication unit of a communication group of the super group located in it.